In various applications for handling elongated members such as tubes and solid rods, a member is often grasped at an end by a chuck which clamps the member by means of a number of radially inwardly driven clamping members. In the case of a hollow tube, the chuck may grip the tube internally by means of a number of radially outwardly driven clamps. Such chucks are used, among other applications, in pipe bending machines wherein a chuck is mounted upon a rotatable drive shaft which in turn is carried by a moving carriage. The chuck is employed to firmly grasp an end of a pipe to be bent which then may be longitudinally advanced toward a set of bend dies by linear motion of the carriage and the chuck. Plane of bend is determined by rotating the pipe, which is achieved by precisely rotating the chuck and its drive shaft on the carriage.
Certain manufacturing operations require the bending of a pipe or tube which has at least one flared end and carries a rotatable fitting thereon. The flaring operation requires a straight tube section of a minimum length for properly holding the tube. Some types of multiple bend tubes do not provide a properly located straight section of adequate length. For this reason, among others, the flaring and application of the fitting to the tube are preferably carried out before bending. Nevertheless, because of difficulties encountered in grasping the end of a previously flared tube and fitting in conventional chucks, it may be necessary to either bend the tube before it is flared and provided with the fitting or complex tube grasping arrangements must be used. In certain applications an additional straight tube section has been tightly threaded to the tube fitting to enable the tube to be grasped in a conventional chuck for the bending operation. Where the tube is too small to receive a conventional internal chuck, the bending or other handling of such flared tubes has presented significant problems.
Accordingly, it is an object of the present invention to provide a chuck that avoids or minimizes the above-mentioned problems and permits the ready handling of flared tubes and tubes with movable fittings thereon.